Cloud9-RoR-mysql連結

https://docs.c9.io/docs/running-a-rails-app  本篇跟這份文件有關
開啟專案下的config/database.yml檔，將內容改成

development:
  adapter: mysql2
  encoding: utf8
  database: c9
  host: <%=ENV['IP']%>
  username: <%=ENV['C9_USER']%>
  password:
production:
  adapter: mysql2
  encoding: utf8
  database: c9
  host: <%=ENV['IP']%>
  username: <%=ENV['C9_USER']%>
  password:
test:
  adapter: mysql2
  encoding: utf8
  database: c9
  host: <%=ENV['IP']%>
  username: <%=ENV['C9_USER']%>
  password:

再打開專案下的Gemfile(就是這一步，我一直再想what is gemfile???)，增加兩行

# Use mysql as the database for Active Record
gem 'mysql2'

接著在指令處下

gem install mysql2

安裝完成

Fetching: mysql2-0.3.19.gem (100%)
Building native extensions.  This could take a while...
Successfully installed mysql2-0.3.19
1 gem installed

Run程式啦

rails s -b $IP -p $PORT

畫面可以正常出現就代表完成啦！

在連線請先確定是不是裝好mysql，才不會鬼打牆。